you definitely should make a couple of games to present your skills if you aim for commissions but it is also a good way to make a type of portfolio. There are websites like newgrounds or scirras arcade section where you can upload your game and earn reputation from it. Sometimes these works get notied and you get contacted by ppl who are looking for talented game creators but if you want to target websites that sell the games, you should still have something to show so they don't think you are a fraud or something. Websites like elance also offer projects that involve html5 game making, I earned there 200$ for making a simple one. Just look trough the forum, im sure there are already topics involving the moneymaking part. Oh, and try to include contact information to your games, it helps in case a potentional client wants to talk to you for a possible deal.